Job offer Refusal?

I had an interview and exam with a company last January, I was positive and confident to get the job that I wanted to. After a month, I still do not receive any mails or updates coming from the company. So I decided to apply for a job to another company, I passed the exams and had an orientation about the job nearly I was about to say yes to the interviewee, I received a call from the previous company that I was applying for and discussing to me about the job offer. For now, I am really confuse on which one to take. Can you please help me to make a refusal letter for the company that I will not take?